$TXDFXOWXUH ² Contents lists available at ScienceDirect Aquaculture journal homepage: www.elsevier.com/locate/aquaculture Short communication Capture, transport, prophylaxis, acclimation, and continuous spawning of Mahi-mahi (Coryphaena hippurus) in captivity John D. Stieglitz⁎, Ronald H. Hoenig, Steven Kloeblen, Carlos E. Tudela, Martin Grosell, Daniel D. Benetti University of Miami, Rosenstiel School of Marine and Atmospheric Science, 4600 Rickenbacker Causeway, Miami, FL 33149-1031, USA ARTICLE INFO ABSTRACT Keywords: Successful culture of marine fish relies upon availability of high quality fertilized eggs obtained from broodstock. Dolphinfish However, some of the most critical aspects of obtaining such eggs are often overlooked. These aspects include the Dorado capture, transport, acclimation, and spawning of sexually mature wild-caught fish. Mahi-mahi (Coryphaena RAS hippurus), also known as dolphinfish, have been identified as one of the most promising candidate species for Broodstock development of warm-water marine finfish aquaculture due to their high growth rate, market presence, and Pelagic global distribution. In addition, mahi-mahi have proven to be a useful model species for physiology and environmental toxicology research, specifically in studies examining tropical and subtropical pelagic teleosts. One of the keys to aquaculture development of this species is the ability to obtain year-round production of fertilized embryos. This study documents the technical methods utilized to reach a point of consistent mahi-mahi egg production year-round, while also detailing the live transport tank and land-based spawning tank design, implementation, and operation. Following three different groups of wild-caught mahi-mahi broodstock from the point of capture throughout their lifespan, this study provides novel information on growth, survival, and spawning of this species in captivity. Results from this research have allowed for significant new insights into the effects of a variety of environmental stressors on the early life stages of this species. Furthermore, the ability to maintain consistent spawning populations of mahi-mahi in captivity has allowed for reliable and consistent production of fully-weaned fingerlings of this species, thereby resolving one of the key industry bottlenecks that has been limiting expansion of mahi-mahi commercial-scale aquaculture. 1. Introduction oping technology for domestication of this species (Hagood et al., 1981; Kraul, 1989; Szyper et al., 1984), yet to date there has been no long- The marine aquaculture sector continues to expand globally as term commercial-scale success with mahi-mahi aquaculture. Reasons advances in technology and efficiency open opportunities for sustained for this are numerous and extend beyond the scope of this study, but growth of this sector. Aside from the dominance of Atlantic salmon they likely center upon the rather consistent availability of wild mahi- (Salmo salar) in the marine finfish aquaculture sector, a variety of other mahi in the marketplace, the significant capital investment required to marine finfish species are cultured in significant quantities throughout grow this species to comparable harvest size with the wild product the world (FishStatJ - Fisheries and aquaculture software, 2016). How- (> 5 kg), and the technological challenges of raising this species on a ever, given the projected gap between seafood supply and demand commercial-scale in captivity. However, given the rising interest in forecasted for the future (Kobayashi et al., 2015), the search for novel developing sources of sustainable seafood and the growing popularity species for the marine finfish aquaculture industry is ongoing. When of plate-size whole-fish in the marketplace, there is a renewed interest selecting new species for commercial aquaculture production, factors in further aquaculture development of mahi-mahi as a means to meet such as market presence, price, availability, ease of culture, and growth these interests. Mahi-mahi can reach plate size (~400–500 g) in less rate represent some of the most important variables to consider. The than half the time required for other species commonly presented in mahi-mahi (Coryphaena hippurus) seemingly has all of the attributes this manner, such as snapper (Lutjanus spp.) and the Mediterranean sea necessary to make it a leading candidate for further aquaculture bass (Dicentrarchus labrax), or branzino as it is more commonly known, development. Beginning in the early 1980's researchers began devel- and their food conversion ratio (FCR) during this growth cycle ranges ⁎ Corresponding author. E-mail address: [email protected] (J.D. Stieglitz). http://dx.doi.org/10.1016/j.aquaculture.2017.05.006 Received 4 November 2016; Received in revised form 3 May 2017; Accepted 5 May 2017 $YDLODEOHRQOLQH0D\ (OVHYLHU%9$OOULJKWVUHVHUYHG J.D. Stieglitz et al. $TXDFXOWXUH ² from 1.5–2.0 (dry feed/live fish) (Benetti et al., 1995; Kraul, 1989). Table 1 Aside from interest in this species from a food-fish perspective the Growth metrics and FCRs of broodstock fish. Values sharing lower case letters within fi rows are not significantly different. Combined gender data not included in statistical mahi-mahi has been identi ed as a promising model species for * ff analyses. Age at capture estimated as described in Section 6. FL = fork length; research examining the e ects of climate change (Bignami et al., TL = total length; DPH = days-post-hatch; GSI = gonadosomatic index; 2014) and open ocean pollution events, such as the Deepwater Horizon HSI = hepatosomatic index; VSI = visceral somatic index; SGR = specific growth rate; oil spill in 2010 (Burggren et al., 2015; Edmunds et al., 2015; Esbaugh AGR = absolute growth rate; RGR = relative growth rate; FCR (w:w) = food conversion fi et al., 2016; Incardona et al., 2014; Mager et al., 2014; Stieglitz et al., ratio of wet food weight: wet sh weight; FCR (d:w) = food conversion ratio of dry food weight: wet fish weight. 2016a). Unlike more commonly cultured marine finfish species such as salmon and sea bass, fertilized embryos of mahi-mahi are not commer- Gender Male Female Combined cially available. Therefore, development of a broodstock program requires the successful capture, acclimation, and spawning of this Mean SE Mean SE Mean SE species on a regular basis in captivity. This same hurdle exists for the n 3 10 13 culture of other relatively novel high-value marine finfish species such as cobia (Rachycentron canadum), tuna (Thunnus spp.), grouper (Epine- Initial FL (cm) 65.5 4.3 65.7 3.4 65.7 2.7 phelus spp. and Mycteropera spp.), and snapper (Lutjanus spp.), yet to Initial TL (cm) 80.5 5.4 78.3 4.0 78.8 3.3 date there is no documented methodology for development of a year- Initial Mass (kg) 2.8 0.5 2.6 0.3 2.6 0.3 fi Initial condition factor (K) 1.0 0.1 0.9 0.0 0.9 0.0 round spawning stock of mahi-mahi. For the rst time, this study Age at capture (DPH)* 369 28.8 424 28.6 411 23.4 documents the successful capture, handling, acclimation, and spawning Days in captivity 149 14.8 95 22.2 108 18.4 of three separate groups of mahi-mahi at the University of Miami Final FL (cm) 111.2a 1.6 92.3b 6.2 96.7 5.2 Experimental Hatchery (UMEH) on Virginia Key, Florida, USA. Building Final TL (cm) 130.2 7.4 109.4 7.3 114.2 6.3 Final mass (kg) 14.9a 0.2 8.1b 1.4 9.7 1.3 upon early research and development efforts with this species, the Final condition factor (K) 1.1 0.1 1.0 0.0 1.0 0.0 following technical methods represent a reliable process that can be GSI (%) 0.6a 0.1 3.5b 0.4 2.8 0.5 successfully applied throughout the world, given the circum-global HSI (%) 1.1a 0.1 2.1b 0.1 1.9 0.2 distribution of mahi-mahi in tropical and subtropical seas. VSI (%) 4.6a 0.3 8.8b 0.6 7.8 0.7 SGR (cm) (%) 0.4 0.1 0.3 0.1 0.3 0.0 SGR (g) (%) 1.2 0.3 1.4 0.2 1.3 0.1 2. Capture and transport AGR (cm day−1) 0.3 0.1 0.2 0.0 0.3 0.0 AGR (g day−1) 83.2 12.8 58.4 4.7 64.1 5.3 Mahi-mahi utilized in this study were caught in the Straits of Florida RGR (cm) (%) 71.2 11.8 43.2 10.6 49.7 9.0 off the coast of Miami, Florida, USA using hook and line angling RGR (g) (%) 471.9 120.3 268.8 67.7 315.6 61.8 fi FCR (w:w) 6.2 1.4 7.6 0.8 7.3 0.7 techniques. While some sh were captured on J-style hooks (Mustad® FCR (d:w) 1.6 0.4 2.0 0.2 1.9 0.2 model 7766 sizes 5/0–7/0, Norway) using trolled feathers and hard plastic lures, the majority of fish were caught using bait, live or dead, on circle hooks (Mustad® model 39938-BLN sizes 3/0–6/0, Norway). By through while reducing sloshing that occurs in offshore sea conditions. using small gap circle hooks craniofacial injuries were minimized While in use the water level of the transport tank was elevated above during the angling process. Captured fish were carefully lifted from the transport tank lid, and this served to minimize the sloshing action of the water, hooks were extracted without physically contacting the fish water inside the transport tank. Compressed oxygen was used to using a commercial de-hooking device (R & R Tackle Co., Miami, supersaturate the transport tank water at a level of 9–12 mg L− 1, while Florida, USA), and then the fish were placed in a custom-modified raw seawater (32–34 ppt salinity) was pumped through the tank at a 1.1 m3 (1.65 m diameter ×0.76 m height) cylindrical polyurethane rate of approximately 1000% daily exchange (~42% of tank volume transport tank (Fig.